John d



UNITED STATES PATENT OFFICE.

JOHN D. HOPE, OF NIAGARA FALLS, NEW YORK, ASISIGNOR TO G. A. GARDNER, OF NEW YORK, N. Y.

ROCK-DRILL.

To all whom t may concern Be it known that I, JOI-IN D. Horn, of Niagara Falls, in the county of Niagara and State of NewYork, have invented a new and Improved Form of 4Drills for Drilling Holes in Rocks; and I do hereby declare that the following is a full and eXact description thereof, reference being had to the accompanying drawings and to the letters of reference marked thereon.

The nature of my invention is in shaping the drill so as to cut a true round hole and also so as to clear'itself from the powdered rock. Also the improved shape strengthens the drill and renders the labor of sharpening much less and prevents great waste of steel and further the form of the cutting edge is such as to insure the greatest execution upon the rock at each blow.

T o enable others to make and use my invention will proceed to describe its construction and operation.

I construct my drill rod or shaft in the usual form and after flattening the steel forming the point of the drill I raise on two of the transverse corners a wing or ridge eX- tending up as far as the steel is ilattened or the whole length of steel where it is inserted into an iron rod, said wings being marked A in the accompanying drawings. I then bring the edges of the center and both wings to a cutting surface causing the two central corners and the corner of one wing marked B to cut an outer circle while the corner of the other wing marked C is brought in toward the center, so that the one wing makes a distinct cut from the other in turning in the hole whereby the rock is pulverized with much ,greater rapidity.

Vhat I claim as my invention and desire to secure by Letters Patent s- Not the shaping the cutting point of the drill into the shape of the letter Z as that form of drill has long been in use but it is thel formation and shaping of the wings or,

ridges on the transverse corners of the drill substantially as described.

J Ol-IN D. HOPE.

Witnesses:

SAMUEL T. CALDWELL, H. S. RANsoM. 

